Technical Details
How spam Filtering Works
We are using SpamAssassin, a "mail filter" that runs on the campus MTAs ("mail transport agents" or email servers) to identify unsolicited commercial email (UCE) or "spam". Using its rule base, SpamAssassin uses a wide range of heuristic tests on mail headers and body text to identify unsolicited commercial email. OIT also has SpamAssassin running on the OIT Mailbox Servers. Some departments are also running it on their mail servers. Check with your Computer Support Coordinator for details.
This is how a typical message is scanned as possible spam.
- All messages addressed to "youremailaddress@uci.edu" will be scanned for spam.
- SpamAssassin will analyze the content of the message and assign a score using its rule base.
- SpamAssassin will insert mail headers that explain the results of the spamassassin
check.
Note: The message headers it adds are not normally displayed by email clients. Use "View full headers" or a similar command to see them.
Here is an example of the type of header information that's added by SpamAssassin:
Score of 5 or higher
X-UCIRVINE-spamcheck: spam, SpamAssassin (score=7.533, required 5, DATE_SPAMWARE_Y2K 4.40, FORGED_MUA_OUTLOOK 1.58, LINES_OF_YELLING 0.01, LINES_OF_YELLING_2 0.10, MISSING_MIMEOLE 1.15, ORDER_NOW 0.28)
X-UCIRVINE-spamscore: sssssssScore of 1 - 5
X-UCIRVINE-Mailscanner: No viruses found
X-UCIRVINE-spamscore: sss
X-NACS_ES-Mailscanner: No viruses found
How the "My Email Options" Simple spam Filter Works
- The Default setting will move any message with a score of 5 or higher to your SPAM folder.
- The Strict setting will move any message with a score of 3 or higher to your SPAM Folder.
RBLs
Our new system will reject connections from mail servers listed on a particular set of "real-time block lists" (RBLs). The RBLs are lists of identified spammers, maintained by a third party. Anybody sending through an RBL-listed server will be unable to deliver mail to UCI. Please note that the sender in such cases will receive a "failed delivery" message which includes instructions on how to get removed from the RBL. Therefore, in those relatively rare instances in which the sender's server has been improperly listed, they will be made aware that the mail they sent was not delivered, and will have an opportunity to fix the problem.
Please note that UCI relies on a well-known, widely respected RBL operated by a non-profit organization called "spamhaus.org". Anybody listed on that RBL will have trouble sending email not only to us, but to thousands of other sites using the same list.
Greylisting
One technique which has seen great success on other UC campuses is known as "greylisting". This mechanism causes senders to delay their messages in a manner which complies with accepted email standards. Spammers generally are unable to cooperate, and therefore their messages are not accepted.
You may notice some delay in receiving expected messages, particularly in the period immediately following our enabling of greylisting. Most of the time, these delays should be minimal (under an hour), and they should only apply to the first message you receive from a particular correspondent. Please let us know if you experience any lengthy delays in received expected messages.
Additional information
For technical information about the RBL we are using, please visit:
To stay informed on future upgrades, service outages, or enhancements to the UCI electronic mail environment, please subscribe to our new email announcements list by clicking here:
